CLE detects intramucosal bacteria in patients with IBD
MedWire News: Patients with inflammatory bowel disease (IBD) have a greater distribution of intramucosal bacteria than those with a normal intestine, show UK researchers who successfully imaged for the bacteria using confocal laser endomicroscopy (CLE).
It is well established that the interaction of intramucosal intestinal bacteria with the immune system plays an important role in the pathogenesis of IBD. Conventional confocal endomicroscopy effectively images bacteria on the mucosal surface, but it is unable to locate bacteria within the gut mucosa.
"[CLE] seems to be superior to other available technologies because bacteria can be observed in vivo during ongoing colonoscopy," say Alastair Watson (University of East Anglia, Norwich) and colleagues.
To specify the distinct endomicroscopic appearance of enteral bacteria , the researchers imaged Escherichia Coli strains expressing enhanced green fluorescent protein in mice and fluorescent human enteric bacteria to specific the distinct endomicroscopic appearance of enteral bacteria.
Mucosal biopsies of endomicroscopic identifiable intramucosal bacteria and negative mucosal areas were then obtained from 21 patients during colonoscopy and correlated with bench-top fluorescence microscopy (FISH).
Using CLE, Watson and team found distinct structures labelled by fluorescein that appeared within epithelial cells or the lamina propria of the mucosa in human bacteria and detected intramucosal bacteria with a sensitivity of 89% and specificity of 100%, as confirmed using FISH as the gold standard.
Retrospective study findings of the frequency of intramucosal bacteria among 27,062 images from 50 healthy individuals, 84 with ulcerative colitis (UC) and 29 with Crohn's disease (CD), revealed a higher frequency of endomicroscopic-identifiable intramucosal bacteria among patients with UC (60%) and CD (66%) compared with controls (14%).
These results were then confirmed in a prospective study of 6634 images from 20 IBD patients and 10 controls, which showed that patients with CD and UC had a significantly wider distribution of involvement with intramucosal bacteria in the colon and terminal ileum compared with controls, at 85.2% and 75.9% versus 16.8%, respectively.
"This new endoscopic technique enables the rapid identification of patients with intramucosal bacteria, and will be a valuable tool in the elucidation of the pathogenesis of IBD and the development of new clinical algorithms," conclude the authors in the journal Gut.
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By Ingrid Grasmo